Different histological patterns of type-V collagen levels confer a matrices-privileged tissue microenvironment for invasion in malignant tumors with prognostic value

Previous studies have reported a close relationship between type V collagen (Col V) and tumor invasion and motility in both breast cancer (BC) and lung cancer (LC). The present work aims to determine whether the extracellular-matrix (ECM)-defined microenvironment influences patient clinical outcome and investigate to which extent histological patterns of Col V expression in malignant cells have a prognostic effect in patients. To that end, we examined the expression of Col V in the tissues of 174 primary tumors (MM, N = 82; LC, N = 41; and BC, N = 46) by immunohistochemistry. We found: (1) diffuse strong green birefringence in membrane and cytoplasm individualizing malignant cells in MM; (2) a focal and weak birefringence mainly in cytoplasmic membrane involving groups of malignant cells in LC and BC; (3) higher average H-score of Col V in MM than in LC and BC samples; (4) a direct correlation between Col V histologic pattern and TNM stage IV, status and median overall survival; (5) patients with LC in TNM stage I, and Col V <= 41.7 IOD/mm2 had a low risk of death and a median survival time more than 20 months; (6) patients with MM in TNM stage IV and Col V > 41.7 IOD/mm2 presented a high risk of death and a median survival time of just 20 months. These findings suggest that high levels of Col V individualizing malignant cells, as observed in MM, and low levels grouping malignant cells, as observed in LC and BC, confers different immune-privileged tissue microenvironment for tumor invasion with impact on prognosis of the patients.